printer-errors.md

Printer Errors ^{7 Kyu}

^{LINK TO THE KATA - FUNDAMENTALS}

Description

In a factory a printer prints labels for boxes. For one kind of boxes the printer has to use colors which, for the sake of simplicity, are named with letters from a to m.

The colors used by the printer are recorded in a control string. For example a "good" control string would be aaabbbbhaijjjm meaning that the printer used three times color a, four times color b, one time color h then one time color a...

Sometimes there are problems: lack of colors, technical malfunction and a "bad" control string is produced e.g. aaaxbbbbyyhwawiwjjjwwm with letters not from a to m.

You have to write a function printer_error which given a string will return the error rate of the printer as a string representing a rational whose numerator is the number of errors and the denominator the length of the control string. Don't reduce this fraction to a simpler expression.

The string has a length greater or equal to one and contains only letters from a to z.

Examples:

s="aaabbbbhaijjjm"
printer_error(s) => "0/14"

s="aaaxbbbbyyhwawiwjjjwwm"
printer_error(s) => "8/22"

Solution

const printerError = string => {
  const limitLower = 'a'.charCodeAt(0)
  const limitUpper = 'm'.charCodeAt(0)

  const errors = string.split('').filter(character => {
    const charCode = character.charCodeAt(0)

    return charCode < limitLower || charCode > limitUpper
  }).length

  return `${errors}/${string.length}`
}